What should `makeSetValue`/`makeGetValue` do for i64?

Right now there seems to be mix behaviors, which doesn't seem like a great situation.

Within the code base there seems to be very limited use of these types. For `makeGetValue` I only see a single use, in the getValue utility function:

```
$ git grep makeGetValue.*i64
src/library_getvalue.js: case 'i64': return {{{ makeGetValue('ptr', '0', 'i64') }}};
```

For `makeSetValue` there are a few more uses:

```
$ git grep makeSetValue.*i64
src/library_getvalue.js: case 'i64': {{{ makeSetValue('ptr', '0', 'value', 'i64') }}}; break;
src/library_sdl.js: {{{ makeSetValue('ptr', C_STRUCTS.SDL_TouchFingerEvent.touchId, 'touch.deviceID', 'i64') }}};
src/library_sdl.js: {{{ makeSetValue('ptr', C_STRUCTS.SDL_TouchFingerEvent.fingerId, 'touch.identifier', 'i64') }}};
src/library_syscall.js: {{{ makeSetValue('buf', C_STRUCTS.stat.st_size, 'stat.size', 'i64') }}};
src/library_syscall.js: {{{ makeSetValue('buf', C_STRUCTS.stat.st_atim.tv_sec, 'Math.floor(atime / 1000)', 'i64') }}};
src/library_syscall.js: {{{ makeSetValue('buf', C_STRUCTS.stat.st_mtim.tv_sec, 'Math.floor(mtime / 1000)', 'i64') }}};
src/library_syscall.js: {{{ makeSetValue('buf', C_STRUCTS.stat.st_ctim.tv_sec, 'Math.floor(ctime / 1000)', 'i64') }}};
src/library_syscall.js: {{{ makeSetValue('buf', C_STRUCTS.stat.st_ino, 'stat.ino', 'i64') }}};
src/library_syscall.js: {{{ makeSetValue('dirp + pos', C_STRUCTS.dirent.d_ino, 'id', 'i64') }}};
src/library_syscall.js: {{{ makeSetValue('dirp + pos', C_STRUCTS.dirent.d_off, '(idx + 1) * struct_size', 'i64') }}};
src/library_wasi.js: {{{ makeSetValue('newOffset', '0', 'stream.position', 'i64') }}};
src/library_wasi.js: // TODO {{{ makeSetValue('pbuf', C_STRUCTS.__wasi_fdstat_t.fs_rights_base, '?', 'i64') }}};
src/library_wasi.js: // TODO {{{ makeSetValue('pbuf', C_STRUCTS.__wasi_fdstat_t.fs_rights_inheriting, '?', 'i64') }}};
src/library_wasmfs_jsimpl.js: {{{ makeSetValue('size_p', 0, 'size', 'i64') }}};
src/library_wasmfs_opfs.js: {{{ makeSetValue('sizePtr', 0, 'size', 'i64') }}};
src/library_wasmfs_opfs.js: {{{ makeSetValue('sizePtr', 0, 'size', 'i64') }}};
src/library_webgpu.js: {{{ makeSetValue('limitsOutPtr', 'limitsPtr + limitOffset', 'limitValue', 'i64') }}};
src/library_websocket.js: {{{ makeSetValue('bufferedAmount', '0', 'socket.bufferedAmount', 'i64') }}};
```

From my reading of the code `makeGetValue` with `i64` but without MEMORY64 simply doesn't do that right thing, so its good that we don't have any users of that code.

`makeSetValue` does do what is perhaps the right thing bug it generates a lot of rather complicated code. I basically expands to this:

```
(tempI64 = [value>>>0,(tempDouble=value,(+(Math.abs(tempDouble))) >= 1.0 ? (tempDouble > 0.0 ? ((Math.min((+(Math.floor((tempDouble)/4294967296.0))), 4294967295.0))|0)>>>0 : (~~((+(Math.ceil((tempDouble - +(((~~(tempDouble)))>>>0))/4294967296.0)))))>>>0) : 0)],HEAP32[((ptr)>>2)] = tempI64[0],HEAP32[(((ptr)+(4))>>2)] = tempI64[1])
```

The goal of this code as far as I can tell (which is generated here: https://github.com/emscripten-core/emscripten/blob/d91e1279cea285f96ab25c9d7d0334db0a446011/src/parseTools.js#L210-L243) is to try to allow numbers outside of the i53/safeInteger range to stored and retrieved, but its imprecise and involves rounding when these values are not withing the i53 range.

My question is, should we be preferring `i53` in the above cases? Are there any cases were we want to allow for rounded values outside of the i53 range?